Integrated circuit and method of manufacturing same

ABSTRACT

An integrated circuit includes a first and a second set of conductive traces. The first set of conductive traces is in a first level and extends in a first direction. The second set of conductive traces is in a second level and extends in a second direction. The second set of conductive traces includes a first conductive trace corresponding to a gate terminal of a first p-type transistor and a gate terminal of a first n-type transistor, and a second conductive trace corresponding to a gate terminal of a second n-type transistor and a gate terminal of a second p-type transistor. The first and second conductive trace are separated from each other in the first direction. The first n-type transistor and the second p-type transistor are part of a first transmission gate. The second n-type transistor and the first p-type transistor are part of a second transmission gate.

PRIORITY CLAIM

The present application is a continuation of U.S. application Ser. No. 16/397,064, filed Apr. 29, 2019, which is a continuation of U.S. application Ser. No. 15/707,469, filed Sep. 18, 2017, now U.S. Pat. No. 10,296,694, issued May 21, 2019, which is a continuation of U.S. application Ser. No. 14/464,407, filed Aug. 20, 2014, now U.S. Pat. No. 9,767,243, issued Sep. 19, 2017, which claims priority to U.S. Provisional Application No. 62/003,395, filed May 27, 2014, the disclosures of which are incorporated herein by reference in their entireties.

BACKGROUND

Integrated circuits (ICs) are often designed with active devices such as transistors, resistors and capacitors connected by conductive traces, such as metal lines and polysilicon lines, to form circuits. The active devices in ICs are formed by a photolithographic process that includes use of photoresists, photolithographic masks (masks), specialized light sources and various etchants. Increasingly dense ICs have numerous benefits in terms of speed, functionality and cost, but cause increasingly difficult design and fabrication problems.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1A is a diagram of a double patterned cell with a horizontal conductive trace orientation in a layout design for integrated circuits, in accordance with some embodiments.

FIG. 1B is a diagram of a double patterned cell with a vertical conductive trace orientation in a layout design for integrated circuits, in accordance with some embodiments.

FIG. 2A is a diagram of a single patterned cell with a horizontal conductive trace orientation in a layout design for integrated circuits, in accordance with some embodiments.

FIG. 2B is a diagram of a single patterned cell with a vertical conductive trace orientation in a layout design for integrated circuits, in accordance with some embodiments.

FIG. 3A is diagram of a double patterned cell in a layout design for integrated circuits, in accordance with some embodiments.

FIG. 3B is diagram of a double patterned cell in a layout design for integrated circuits, in accordance with some embodiments.

FIG. 4 is circuit diagram of a transmission gate corresponding to a layout design for integrated circuits, in accordance with some embodiments.

FIG. 5 is diagram of a layout design with a transmission gate cell for integrated circuits, in accordance with some embodiments.

FIG. 6 is diagram of a layout design with a transmission gate cell for integrated circuits, in accordance with some embodiments.

FIG. 7 is diagram of a layout design with a transmission gate cell for integrated circuits, in accordance with some embodiments.

FIG. 8 is diagram of a layout design with a transmission gate cell for integrated circuits, in accordance with some embodiments.

FIG. 9 is diagram of a layout design with a transmission gate cell for integrated circuits, in accordance with some embodiments.

FIG. 10 is diagram of a layout design with a transmission gate cell for integrated circuits, in accordance with some embodiments.

FIG. 11 is diagram of a layout design with a transmission gate cell for integrated circuits, in accordance with some embodiments.

FIG. 12 is diagram of a layout design with a transmission gate cell for integrated circuits, in accordance with some embodiments.

FIG. 13 is diagram of a layout design with a transmission gate cell for integrated circuits, in accordance with some embodiments.

FIG. 14 is diagram of a layout design with a transmission gate cell for integrated circuits, in accordance with some embodiments.

FIG. 15 is diagram of a layout design with a transmission gate cell for integrated circuits, in accordance with some embodiments.

FIG. 16 is a flow chart of a method of layout design for integrated circuits, in accordance with some embodiments.

FIG. 17 is a block diagram of a computer system portion of a layout design for integrated circuits system, in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

Over time, increasingly dense ICs incorporating progressively smaller physical dimensions have correspondingly made many aspects of IC design and fabrication difficult or even impossible with prior methods. In some embodiments, improved IC design and fabrication methods include a system and method of layout design for ICs that increase packing efficiency of conductive traces, such as metal lines in metal layers created by BEOL processes.

The IC fabrication process is often considered to include a front-end-of-line (FEOL) portion, a middle-end-of-line (MEOL) portion, also called a Middle-Of-The-Line (MOL) portion, and a back-end-of-line (BEOL) portion. FEOL is the first portion of IC fabrication wherein individual active devices are patterned on a semiconductor wafer. FEOL processes include: selecting the type of semiconductor wafer to be used; chemical-mechanical planarization and cleaning of the wafer; shallow trench isolation (STI); well formation, gate module formation, and source and drain creation. FEOL does not include the deposition of metal interconnect layers. MEOL processes occur after FEOL processes and include gate contact formation and under bump metallization (UBM) processes.

BEOL is the final portion of the IC fabrication process where the individual devices (transistors, capacitors, resistors, etc.) are interconnected with vias and conductive traces, e.g., metal lines. BEOL generally begins when the first layer of metal is deposited and includes contacts, insulating layers (dielectrics), metal levels, and bonding sites for chip-to-package connections. In some embodiments, ten or more metal layers are added in the BEOL portion.

In some embodiments, the system and method of layout design for ICs increases packing efficiency of conductive traces, such as metal lines in metal layers created by BEOL processes, by routing all metal lines in one direction on each metal layer. Routing all metal lines in one direction on each metal layer enables greater packing density through a more efficient packing of conductive traces. Routing all metal lines in one direction also makes it possible to relax pitch requirements between conductive traces, as set forth by one or more design rules, because metal structures having metal lines routed in one direction have a regular pattern that reduces the risk of manufacturing or process errors. In some embodiments, a double patterning process creates sets of metal lines all oriented in a single direction.

FIG. 1A is a diagram of a double patterned cell with a horizontal conductive trace orientation in a layout design for integrated circuits 100, in accordance with some embodiments. A first set of conductive traces 102 is oriented in a single direction. In some embodiments, the first set of conductive traces 102 is oriented in a horizontal direction with respect to the page orientation. In some embodiments, the conductive traces in the first set of conductive traces 102 are parallel metal lines in the same metal layer. As used herein the term “line” includes one or more line segments. The first set of conductive traces 102 is formed by photolithographic techniques using a first mask. Pitch is the spacing between repeating portions of adjacent conductive traces, such as similarly, repetitively positioned corners of adjacent conductive traces. The first mask, and correspondingly, the first set of conductive traces 102, has a predetermined pitch.

A second set of conductive traces 104 is oriented in the same direction as the first set of conductive traces 102. In some embodiments, the second set of conductive traces 102 is oriented in a horizontal direction. In some embodiments, the conductive traces in the second set of conductive traces 104 are parallel metal lines in the same metal layer. The second set of conductive traces 102 is formed by photolithographic techniques using a second mask. The second mask, and correspondingly, the second set of conductive traces 104, has a predetermined pitch. In some embodiments, the pitch of the first mask and the pitch of the second mask are the same. Furthermore, the second mask is positioned such that the second mask is offset with respect to the first mask by less than the pitch for the first set of conductive traces 102. Together, the first set of conductive traces 102 and the second set of conductive traces 104 are formed by double patterning. Double patterning is the formation of features on a layer with two offset masks to create features smaller than a pitch of either mask. Double patterning is performed in the fabrication of ICs to increase the density of features patterned by the masks beyond that enabled by layers formed with a single mask.

A set of metal-like defined (MD) conductive traces 106 in an MD layer is formed during the MEOL portion of the IC fabrication process. In some embodiments, the set of MD conductive traces 106 is conductive, but comprises a greater percentage of nonmetal material compared to metal material. In some embodiments, the set of MD conductive traces 106 is formed of a semiconductor using ion implantation sufficient to convert the semiconductor into a conductor. A double patterned cell 108 includes the set of MD conductive traces 106 formed during the MEOL portion of IC fabrication, and the first set of conductive traces 102 and the second set of conductive traces 104 formed during the BEOL portion of IC fabrication. The cell 108 has one or more active devices formed and electrically connected in the cell.

FIG. 1B is similar to FIG. 1A rotated by 90 degrees. A first set of conductive traces 102′ corresponds to the first set of conductive traces 102 (FIG. 1A) rotated 90 degrees, however, there are four conductive traces in FIG. 1B. A second set of conductive traces 104′ corresponds to the first set of conductive traces 104 (FIG. 1A) rotated 90 degrees, however, there are three conductive traces 104′ in FIG. 1B. A first set of MD conductive traces 106′ corresponds to the first set of MD conductive traces 106 (FIG. 1A) rotated 90 degrees, however, there are six MD conductive traces 106′ in FIG. 1B. A double patterned cell 108′ corresponds to the double patterned cell 108 (FIG. 1A) rotated 90 degrees.

FIG. 2A is a diagram of a single patterned cell with a horizontal conductive trace orientation in a layout design for integrated circuits 200, in accordance with some embodiments. A set of conductive traces 202 is oriented in a single direction. In some embodiments, the set of conductive traces 202 is oriented in a horizontal direction. In some embodiments, the conductive traces in the set of conductive traces 202 are parallel metal lines in the same metal layer. In some embodiments, a number of the conductive traces in the set of conductive traces 202 is greater than 4. The set of conductive traces 202 is formed by photolithographic techniques using a mask having a predetermined pitch. The set of conductive traces 202 is formed by single patterning. Single patterning is the formation of features on a layer with one mask. Conductive traces formed by single patterning typically have lower densities than conductive traces formed by double patterning.

A set of MD conductive traces 206 in an MD layer is formed during the MEOL portion of the IC fabrication process. In some embodiments, the set of MD conductive traces 206 is conductive, but comprises a greater percentage of nonmetal material compared to metal material. In some embodiments, the set of MD conductive traces 206 is formed of a semiconductor using ion implantation sufficient to convert the semiconductor into a conductor. A single patterned cell 208 includes the set of MD conductive traces 206 formed during the MEOL portion of IC fabrication, and the set of conductive traces 202 formed during the BEOL portion of IC fabrication. The cell 208 has one or more active devices formed and electrically connected in the cell.

FIG. 2B is similar to FIG. 2A rotated by 90 degrees. A first set of conductive traces 202′ corresponds to the first set of conductive traces 202 (FIG. 2A) rotated 90 degrees, however, there are seven conductive traces in FIG. 2B. A first set of MD conductive traces 206′ corresponds to the first set of MD conductive traces 206 (FIG. 2A) rotated 90 degrees, however, there are six MD conductive traces 206′ in FIG. 2B. A double patterned cell 208′ corresponds to the double patterned cell 208 (FIG. 2A) rotated 90 degrees.

FIG. 3A is diagram of a double patterned cell 308 in a layout design for integrated circuits 300, in accordance with some embodiments. A first set of conductive traces 302 is oriented in a single direction. In some embodiments, the first set of conductive traces 302 includes an even-numbered quantity of conductive traces 302 oriented in a horizontal direction. In some embodiments, the conductive traces in the first set of conductive traces 302 are parallel metal lines in the same metal layer. The first set of conductive traces 302 is formed by photolithographic techniques using a first mask. The first mask, and correspondingly, the first set of conductive traces 302, has a predetermined pitch. In some embodiments, the pitch ranges from about 80 nanometers (nm) to about 100 nm.

A second set of conductive traces 304 is oriented in the same direction as the first set of conductive traces 302. In some embodiments, the second set of conductive traces 304 includes an even-numbered quantity of conductive traces 304 oriented in a horizontal direction. In some embodiments, the conductive traces in the second set of conductive traces 304 are parallel metal lines in the same metal layer. The second set of conductive traces 304 is formed by photolithographic techniques using a second mask. The second mask, and correspondingly, the second set of conductive traces 304, has a predetermined pitch. In some embodiments, the pitch of the first mask is equal to the pitch of the second mask. In some embodiments, the pitch of the first mask and the pitch of the second mask ranges from about 80 nm to about 100 nm. In some embodiments, the pitch of the second set of conductive traces 304 ranges from about 80 nm to about 100 nm.

The second mask is positioned such that the second mask is offset with respect to the first mask by less than the pitch for the first set of conductive traces 302. The pitch of the first set of conductive traces 302 to the second set of conductive traces 304 (i.e., the distance between the first set of conductive traces 302 and the second set of conductive traces 304) ranges from about 40 nm to about 80 nm. Together, each of the first set of conductive traces 302 and the second set of conductive traces 304 are formed by double patterning. Vias 306 electrically connect conductive traces in the first set of conductive traces 302 and the second set of conductive traces 304 to conductive traces in one or more other layers.

Cell 308 includes a conductive trace 302 that is a power rail LB and a conductive trace 304 that is a power rail LA. Cell 308 has an even-numbered total quantity of conductive traces 302 and 304 between the power rail LB and the power rail LA.

FIG. 3B is diagram of a double patterned cell 308′ in a layout design for integrated circuits 300, in accordance with some embodiments. Double patterned cell 308′ is similar to double patterned cell 308, but includes a different quantity of conductive traces. A first set of conductive traces 302′ corresponds to the first set of conductive traces 302 (FIG. 3A), however, there is an odd-numbered quantity of conductive traces included in the first set of conductive traces 302′ in FIG. 3B. A second set of conductive traces 304′ corresponds to the second set of conductive traces 304 (FIG. 3A), the second set of conductive traces 304′ includes an even-numbered quantity of line segments. Vias 306′ correspond to vias 306 (FIG. 3A) and electrically connect conductive traces in the first set of conductive traces 302′ and the second set of conductive traces 304′ to conductive traces in one or more other layers within cell 308′.

Cell 308′ includes a first conductive trace 302′ that is a first power rail LB and a second conductive trace 302′ that is a second power rail LB. Cell 308′ has an odd-numbered total quantity of conductive traces 302′ and 304′ between the first power rail LB and the second power rail LB.

FIG. 4 is a circuit diagram of a transmission gate corresponding to a layout design for integrated circuits 400, in accordance with some embodiments. A first positive-type metal oxide semiconductor (PMOS) transistor 402 includes a gate terminal A1, a drain (D) terminal and a source (S) terminal. A first negative-type metal oxide semiconductor (NMOS) transistor 404 includes a gate terminal B2, a D terminal and an S terminal. The D terminal of the first PMOS transistor 402 is electrically connected to the S terminal of the first NMOS transistor 404 and the S terminal of the first PMOS transistor is electrically connected to the D terminal of the first NMOS transistor to form a first transistor pair.

A second PMOS transistor 406 includes a gate terminal B1, a D terminal and an S terminal. A second NMOS transistor 404 includes a gate terminal A2, a D terminal and an S terminal. The D terminal of the second PMOS transistor 406 is electrically connected to the S terminal of the second NMOS transistor 408 and the S terminal of the second PMOS transistor is electrically connected to the D terminal of the second NMOS transistor to form a second transistor pair.

Gate terminal A1 of first PMOS transistor 402 is electrically coupled to gate terminal A2 of second NMOS transistor 408. Gate terminal B1 of second PMOS transistor 406 is electrically coupled to gate terminal B2 of first NMOS transistor 404. The S terminal of the first PMOS transistor 402 and the D terminal of the first NMOS transistor 404 are electrically coupled to the D terminal of the second PMOS transistor 406 and the S terminal of the second NMOS transistor 408 to form a transmission gate 400. In some embodiments, the transmission gate 400 is in a single cell.

FIG. 5 is diagram of a layout design with a transmission gate cell for integrated circuits 500, in accordance with some embodiments. The transmission gate cell 500 corresponds to the transmission gate of FIG. 4, e.g., a gate terminal A1 of a first PMOS transistor is electrically connected to a gate terminal A2 of a second NMOS transistor and a gate terminal B1 of a second PMOS transistor is electrically connected to a gate terminal B2 of a first NMOS transistor. As used herein, the phrase “electrically connected” includes the phrase “conductively connected.” In some embodiments, the transmission gate cell 500 includes metal 1 (M1) portions, MD 2 (MD2) portions, via 0 (V0) portions, metal-polysilicon connected (MP) portions, oxide definition (OD) portions, polysilicon (Poly) portions and cut polysilicon (CPO) portions. In some embodiments, the M1 portions are contained in part of a metal layer in the transmission gate cell 500. In some embodiments, the M1 portions are part of the only metal layer in the transmission gate cell 500. In some embodiments, the M1 portions are positioned in one direction by double patterning with a first mask pattern and a second mask pattern.

In some embodiments, the Poly portions are also referred to as a set of conductive features extending along a first predetermined direction in a conductive layer, i.e., the polysilicon layer. In some embodiments, the MD2 portions are also referred to as a set of conductive features extending along the first predetermined direction in a conductive layer, i.e., the MD2 layer. In some embodiments, the M1 portions are also referred to as a set of conductive features extending along a second predetermined direction in a conductive layer, i.e., the M1 layer.

In some embodiments, the transmission gate cell 500 includes four conductive traces in a first set of conductive traces 502 and three conductive traces in a second set of conductive traces 504, equaling a total of seven conductive traces. In some embodiments, the first set of conductive traces 502 and the second set of conductive traces 504 are double patterned as M1 portions of a metal layer. In some embodiments, the first set of conductive traces 502 and the second set of conductive traces 504 are double patterned as seven metal lines in M1 portions of a metal layer.

Gate terminals A1, A2, B1 and B2 are formed of Poly portions. Gate terminal Al in a first Poly portion is electrically connected through a first via V0_1 portion to a first M1 metal portion, the first M1 metal portion is electrically connected through a second via portion to an MD2 portion, the MD2 portion is electrically connected through a third via portion to a second M1 portion, the second M1 portion is electrically connected through a fourth via v0_4 to gate terminal A2 in a second Poly portion.

Gate terminal B1 in a third Poly portion is electrically connected through a fifth via V0_2 portion to a third M1 metal portion, the third M1 metal portion is electrically connected through a sixth via portion to a fourth Poly portion, the fourth Poly portion is electrically connected through a seventh via portion to a fourth M1 portion, the fourth M1 portion is electrically connected through a eighth via v0_3 to gate terminal B2 in a fourth Poly portion. In some embodiments, the transmission gate cell 500 includes at least six Poly portions. In some embodiments, the transmission gate cell 500 includes ten Poly portions.

In some embodiments, the conductive traces in the first conductive layer number five between a conductive trace electrically coupled to a power supply voltage and a conductive trace electrically coupled to a ground voltage, e.g., to form the transmission gate cell.

FIG. 6 is diagram of a layout design with a transmission gate cell for integrated circuits 600, in accordance with some embodiments. Except as described herein and illustrated in FIG. 6, the description herein associated with FIG. 5 is applicable to FIG. 6. In some embodiments, the transmission gate cell 600 includes four conductive traces in a first set of conductive traces 602 and three conductive traces in a second set of conductive traces 604, equaling a total of seven conductive traces. In some embodiments, the first set of conductive traces 602 and the second set of conductive traces 604 are double patterned as M1 portions of a metal layer. In some embodiments, the first set of conductive traces 602 and the second set of conductive traces 604 are double patterned as seven metal lines in M1 portions of a metal layer.

Gate terminals A1, A2, B1 and B2 are formed of Poly portions. Gate terminal A1 in a first Poly portion is electrically connected through a first via V0_1 portion to a first M1 metal portion, the first M1 metal portion is electrically connected through a second via portion to an MD2 portion, the MD2 portion is electrically connected through a third via portion to a second M1 portion, the second M1 portion is electrically connected through a fourth via v0_4 to gate terminal A2 in a second Poly portion.

Gate terminal B1 in a third Poly portion is electrically connected through a fifth via V0_2 portion to a third M1 metal portion, the third M1 metal portion is electrically connected through a sixth via portion to a fourth Poly portion, the fourth Poly portion is electrically connected through a seventh via portion to a fourth M1 portion, the fourth M1 portion is electrically connected through a eighth via v0_3 to gate terminal B2 in a fourth Poly portion. In some embodiments, the transmission gate cell 600 includes at least six Poly portions. In some embodiments, the transmission gate cell 600 includes seven Poly portions.

FIG. 7 is diagram of a layout design with a transmission gate cell for integrated circuits 700, in accordance with some embodiments. Except as described herein and illustrated in FIG. 7, the description herein associated with FIG. 5 is applicable to FIG. 7. In some embodiments, the transmission gate cell 700 includes two conductive traces in a first set of conductive traces 702 and two conductive traces in a second set of conductive traces 704, equating to a total of four conductive traces. In some embodiments, the first set of conductive traces 702 and the second set of conductive traces 704 are double patterned as M1 portions of a metal layer. In some embodiments, the first set of conductive traces 702 and the second set of conductive traces 704 are double patterned as four metal lines in M1 portions of a metal layer.

Gate terminals A1, A2, B1 and B2 are formed of Poly portions. Gate terminal A1 in a first Poly portion is electrically connected through a first via V0_1 portion to a first M1 metal portion, the first M1 metal portion is electrically connected through a second via portion to an MD2 portion, the MD2 portion is electrically connected through a third via portion to a second M1 portion, the second M1 portion is electrically connected through a fourth via v0_4 to gate terminal A2 in a second Poly portion.

Gate terminal B1 in a third Poly portion is electrically connected through a fifth via V0_2 portion to a third M1 metal portion, the third M1 metal portion is electrically connected through a sixth via portion to a fourth Poly portion, the fourth Poly portion is electrically connected through a seventh via portion to a fourth M1 portion, the fourth M1 portion is electrically connected through a eighth via v0_3 to gate terminal B2 in a fourth Poly portion. In some embodiments, the transmission gate cell 700 includes at least six Poly portions. In some embodiments, the transmission gate cell 700 includes eight Poly portions.

FIG. 8 is diagram of a layout design with a transmission gate cell for integrated circuits 800, in accordance with some embodiments. Except as described herein and illustrated in FIG. 8, the description herein associated with FIG. 5 is applicable to FIG. 8. In some embodiments, the transmission gate cell 800 includes three conductive traces in a first set of conductive traces 802 and two conductive traces in a second set of conductive traces 804, equating to a total of five conductive traces. In some embodiments, the first set of conductive traces 802 and the second set of conductive traces 804 are double patterned as M1 portions of a metal layer. In some embodiments, the first set of conductive traces 802 and the second set of conductive traces 804 are double patterned as five metal lines in M1 portions of a metal layer.

Gate terminals A1, A2, B1 and B2 are formed of Poly portions. Gate terminal A1 shares a first Poly portion with gate terminal A2. The first Poly portion is electrically connected through a first via V0_2 to a first M1 metal portion.

Gate terminal B1 in a second Poly portion is electrically connected through a second via V0_3 portion to a second M1 metal portion, the second M1 metal portion is electrically connected through a third via v0_1 portion to gate terminal B2 in a third Poly portion. In some embodiments, the transmission gate cell 800 includes at least three unbroken Poly portions. Unbroken Poly portions are not separated vertically from one or more other Poly portions. In some embodiments, the transmission gate cell 800 includes five Poly portions.

FIG. 9 is diagram of a layout design with a transmission gate cell for integrated circuits 900, in accordance with some embodiments. Except as described herein and illustrated in FIG. 9, the description herein associated with FIG. 5 is applicable to FIG. 9. In some embodiments, the transmission gate cell 900 includes two conductive traces in a first set of conductive traces 902 and two conductive traces in a second set of conductive traces 904, equating to a total of four conductive traces. In some embodiments, the first set of conductive traces 902 and the second set of conductive traces 904 are double patterned as M1 portions of a metal layer. In some embodiments, the first set of conductive traces 902 and the second set of conductive traces 904 are double patterned as four metal lines in M1 portions of a metal layer.

Gate terminals A1, A2, B1 and B2 are formed of Poly portions. Gate terminal A1 shares a first Poly portion with gate terminal A2. The first Poly portion is electrically connected through a first via V0_2 to a first M1 metal portion.

Gate terminal B1 in a second Poly portion is electrically connected through a second via V0_1 portion to a second M1 metal portion, the second M1 metal portion is electrically connected through a third via v0_3 portion to gate terminal B2 in a third Poly portion. In some embodiments, a bottom portion of the first Poly portion forms a first dummy transistor. In some embodiments, a MP portion forms a second dummy transistor. In some embodiments, the transmission gate cell 900 includes at least three unbroken Poly portions. In some embodiments, the transmission gate cell 900 includes six Poly portions.

FIG. 10 is diagram of a layout design with a transmission gate cell for integrated circuits 1000, in accordance with some embodiments. Except as described herein and illustrated in FIG. 10, the description herein associated with FIG. 5 is applicable to FIG. 10. In some embodiments, the transmission gate cell 1000 includes two conductive traces in a first set of conductive traces 1002 and one conductive trace in a second set of conductive traces 1004, equating to a total of three conductive traces. In some embodiments, the first set of conductive traces 1002 and the second set of conductive traces 1004 are double patterned as M1 portions of a metal layer. In some embodiments, the first set of conductive traces 1002 and the second set of conductive traces 1004 are double patterned as three metal lines in M1 portions of a metal layer.

Gate terminals A1, A2, B1 and B2 are formed of Poly portions. Gate terminal A1 shares a first Poly portion with gate terminal A2. The first Poly portion is electrically connected through a first via V0_2 to a first M1 metal portion.

Gate terminal B1 in a second Poly portion is electrically connected through a second via V0_1 portion to a second M1 metal portion, the second M1 metal portion is electrically connected through a third via v0_3 portion to gate terminal B2 in a third Poly portion. In some embodiments, a bottom portion of the first Poly portion forms a first dummy transistor. In some embodiments, a MP portion forms a second dummy transistor. In some embodiments, the transmission gate cell 1000 includes at least three unbroken Poly portions. In some embodiments, the transmission gate cell 1000 includes seven Poly portions.

FIG. 11 is diagram of a layout design with a transmission gate cell for integrated circuits 1100, in accordance with some embodiments. Except as described herein and illustrated in FIG. 11, the description herein associated with FIG. 5 is applicable to FIG. 11. In some embodiments, the transmission gate cell 1100 includes three conductive traces in a first set of conductive traces 1102 and two conductive traces in a second set of conductive traces 1104, equating to a total of five conductive traces. In some embodiments, the first set of conductive traces 1102 and the second set of conductive traces 1104 are double patterned as M1 portions of a metal layer. In some embodiments, the first set of conductive traces 1102 and the second set of conductive traces 1104 are double patterned as five metal lines in M1 portions of a metal layer.

Gate terminals A1, A2, B1 and B2 are formed of Poly portions. Gate terminal A1 in a first Poly portion is electrically connected through a first via V0_1 portion to a first M1 metal portion, the first M1 metal portion is electrically connected through a second via V0_2 portion to gate terminal A2 in a second Poly portion.

Gate terminal B1 in a second Poly portion is electrically connected through a third via V0_3 portion to a second M1 metal portion, the second M1 metal portion is electrically connected through a third via v0_4 portion to gate terminal B2 in a fourth Poly portion. In some embodiments, a bottom portion of the third Poly portion forms a dummy transistor. In some embodiments, the transmission gate cell 1100 includes at least six Poly portions. In some embodiments, the transmission gate cell 1100 includes six Poly portions.

FIG. 12 is diagram of a layout design with a transmission gate cell for integrated circuits 1200, in accordance with some embodiments. Except as described herein and illustrated in FIG. 12, the description herein associated with FIG. 5 is applicable to FIG. 12. In some embodiments, the transmission gate cell 1200 includes two conductive traces in a first set of conductive traces 1202 and two conductive traces in a second set of conductive traces 1204, equating to a total of four conductive traces. In some embodiments, the first set of conductive traces 1202 and the second set of conductive traces 1204 are double patterned as M1 portions of a metal layer. In some embodiments, the first set of conductive traces 1202 and the second set of conductive traces 1204 are double patterned as four metal lines in M1 portions of a metal layer.

Gate terminals A1, A2, B1 and B2 are formed of Poly portions. Gate terminal A1 in a first Poly portion is electrically connected through a first via V0_1 portion to a first M1 metal portion, the first M1 metal portion is electrically connected through a second via V0_2 portion to gate terminal A2 in a second Poly portion.

Gate terminal B1 in a third Poly portion is electrically connected through a third via V0_3 portion to a second M1 metal portion, the second M1 metal portion is electrically connected through a fourth via v0_4 portion to gate terminal B2 in the first Poly portion. In some embodiments, a bottom portion of the third Poly portion forms a dummy transistor. In some embodiments, the transmission gate cell 1200 includes at least six Poly portions. In some embodiments, the transmission gate cell 1200 includes six Poly portions.

FIG. 13 is diagram of a layout design with a transmission gate cell for integrated circuits 1300, in accordance with some embodiments. Except as described herein and illustrated in FIG. 13, the description herein associated with FIG. 5 is applicable to FIG. 13. In some embodiments, the transmission gate cell 1300 includes two conductive traces in a first set of conductive traces 1302 and two conductive traces in a second set of conductive traces 1304, equating to a total of four conductive traces. In some embodiments, the first set of conductive traces 1302 and the second set of conductive traces 1304 are double patterned as M1 portions of a metal layer. In some embodiments, the first set of conductive traces 1302 and the second set of conductive traces 1304 are double patterned as four metal lines in M1 portions of a metal layer.

Gate terminals A1, A2, B1 and B2 are formed of Poly portions. Gate terminal A1 in a first Poly portion is electrically connected through a first via V0_1 portion to a first M1 metal portion, the first M1 metal portion is electrically connected through a second via V0_2 portion to gate terminal A2 in a second Poly portion.

Gate terminal B1 in a third Poly portion is electrically connected through a third via V0_3 portion to a second M1 metal portion, the second M1 metal portion is electrically connected through a fourth via v0_4 portion to gate terminal B2 in the first Poly portion. In some embodiments, a top portion of the second Poly portion forms a dummy transistor. In some embodiments, a bottom portion of the third Poly portion forms a dummy transistor. In some embodiments, the transmission gate cell 1300 includes at least six Poly portions. In some embodiments, the transmission gate cell 1300 includes six Poly portions.

FIG. 14 is diagram of a layout design with a transmission gate cell for integrated circuits 1400, in accordance with some embodiments. Except as described herein and illustrated in FIG. 14, the description herein associated with FIG. 5 is applicable to FIG. 14. In some embodiments, the transmission gate cell 1400 includes four conductive traces in a first set of conductive traces 1402 and three conductive traces in a second set of conductive traces 1404, equating to a total of seven conductive traces. In some embodiments, the first set of conductive traces 1402 and the second set of conductive traces 1404 are double patterned as M1 portions of a metal layer. In some embodiments, the first set of conductive traces 1402 and the second set of conductive traces 1404 are double patterned as seven metal lines in M1 portions of a metal layer.

Gate terminals A1, A2, B1 and B2 are formed of Poly portions. Gate terminal A1 shares a first Poly portion with gate terminal A2. The first Poly portion is electrically connected through a first via V0_A to a first M1 metal portion.

Gate terminal B1 shares a second Poly portion with gate terminal B2. The second Poly portion is electrically connected through a second via V0_B to a second M1 metal portion. In some embodiments, the transmission gate cell 1400 includes at least four Poly portions. In some embodiments, the transmission gate cell 1400 includes six Poly portions.

FIG. 15 is diagram of a layout design with a transmission gate cell for integrated circuits 1500, in accordance with some embodiments. Except as described herein and illustrated in FIG. 15, the description herein associated with FIG. 5 is applicable to FIG. 15. In some embodiments, the transmission gate cell 1500 includes four conductive traces in a first set of conductive traces 1502 and three conductive traces in a second set of conductive traces 1504, equating to a total of seven conductive traces. In some embodiments, the first set of conductive traces 1502 and the second set of conductive traces 1504 are double patterned as M1 portions of a metal layer. In some embodiments, the first set of conductive traces 1502 and the second set of conductive traces 1504 are double patterned as seven metal lines in M1 portions of a metal layer.

Gate terminals A1, A2, B1 and B2 are formed of Poly portions. Gate terminal A1 shares a first Poly portion with gate terminal A2. The first Poly portion is electrically connected through a first via V0_A to a first M1 metal portion.

Gate terminal B1 shares a second Poly portion with gate terminal B2. The second Poly portion is electrically connected through a second via V0_B to a second M1 metal portion. In some embodiments, the transmission gate cell 1500 includes at least four Poly portions. In some embodiments, the transmission gate cell 1500 includes six Poly portions.

FIG. 16 is a flow chart of a method of layout design for integrated circuits 1600, in accordance with some embodiments. The method 1600 is performed by a programmed processor executing a set of instructions. In operation 1602, all conductive traces in a first conductive layer that are formed using a first mask pattern are positioned in a first direction. In some embodiments the conductive traces formed using the first mask pattern are parallel metal lines. In operation 1604, all conductive traces in the first conductive layer that are formed using a second mask pattern are positioned in the first direction. In some embodiments, the conductive traces formed using the second mask pattern are parallel metal lines. In some embodiments, the second mask pattern is offset from the first mask pattern by less than a pitch of the first mask pattern.

In operation 1606, all conductive traces in a second conductive layer that are formed using a third mask pattern are positioned in a second direction. In some embodiments the conductive traces formed using the third mask pattern are parallel polysilicon lines. In operation 1608, all conductive traces in the second conductive layer that are formed using a fourth mask pattern are positioned in the second direction. In some embodiments, the conductive traces formed using the fourth mask pattern are parallel polysilicon lines. In some embodiments, the third mask pattern is offset from the fourth mask pattern by less than a pitch of the third mask pattern. In some embodiments the first direction at a right angle to the second direction. In some embodiments the first direction is horizontal and the second direction is vertical. In some embodiments the first direction is vertical and the second direction is horizontal. In operation 1610, at least one via is formed to electrically connect the first conductive layer and the second conductive layer.

FIG. 17 is a block diagram of a computer system 1700 portion of a layout design for integrated circuits system, in accordance with some embodiments In some embodiments, the computer system 1700 executes a set of instructions to perform the method of layout design for integrated circuits 1600 (FIG. 16). Computer system 1700 includes a hardware processor 1782 and a non-transitory, computer readable storage medium 1784 encoded with, i.e., storing, the computer program code 1786, i.e., a set of executable instructions. The processor 1782 is electrically coupled to the computer readable storage medium 1784 via a bus 1788. The processor 1782 is also electrically coupled to an I/O interface 1790 by bus 1788. A network interface 1792 is also electrically connected to the processor 1782 via bus 1788. Network interface 1792 is connected to a network 1794, so that processor 1782 and computer readable storage medium 1784 are capable of connecting and communicating to external elements via network 1794. The processor 1782 is configured to execute the computer program code 1786 encoded in the computer readable storage medium 1784 in order to cause computer system 1700 to be usable for performing a portion or all of the operations as described with respect to the method of layout design for integrated circuits 1600 (FIG. 16).

In some embodiments, the computer program code 1786 includes an instruction 1796 to position all conductive traces on a first conductive layer using a first mask pattern in a first direction. An instruction 1797 positions all conductive traces on the first conductive layer using a second mask pattern in the first direction. An instruction 1798 positions all conductive traces on a second conductive layer in a second direction using a third mask pattern and a fourth mask pattern. An instruction 1799 electrically connects conductive traces in the first conductive layer and the second conductive layer using at least one via. In some embodiments, the first direction is at a right angle to the second direction.

In some embodiments, the processor 1782 is a central processing unit (CPU), a multi-processor, a distributed processing system, an application specific integrated circuit (ASIC), and/or a suitable processing unit.

In some embodiments, the computer readable storage medium 1784 is an electronic, magnetic, optical, electromagnetic, infrared, and/or a semiconductor system (or apparatus or device). For example, the computer readable storage medium 1784 includes a semiconductor or solid-state memory, a magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk, and/or an optical disk. In some embodiments, using optical disks, the computer readable storage medium 1784 includes a compact disk-read only memory (CD-ROM), a compact disk-read/write (CD-R/W), a digital video disc (DVD) and/or Blu-Ray Disk.

In some embodiments, the storage medium 1784 stores the computer program code 1786 configured to cause computer system 1700 to perform the operations as described with respect to the method of layout design for integrated circuits 1600 (FIG. 16).

In some embodiments, the storage medium 1784 stores instructions 1786 for interfacing with external components. The instructions 1786 enable processor 1782 to generate operating instructions readable by a system for performing the method of layout design for integrated circuits 1600 (FIG. 16).

Computer system 1700 includes I/O interface 1790. I/O interface 1790 is coupled to external circuitry. In some embodiments, I/O interface 1790 includes a keyboard, keypad, mouse, trackball, trackpad, and/or cursor direction keys for communicating information and commands to processor 1782.

Computer system 1700 also includes network interface 1792 coupled to the processor 1782. Network interface 1792 allows computer system 1700 to communicate with network 1794, to which one or more other computer systems are connected. Network interface 1792 includes wireless network interfaces such as BLUETOOTH, WIFI, WIMAX, GPRS, or WCDMA; or wired network interface such as ETHERNET, USB, or IEEE-1394.

Computer system 1700 also includes inductive loop interface 1795 coupled to the processor 1782. Inductive loop interface 1795 allows computer system 1700 to communicate with external devices, to which one or more other computer systems are connected. In some embodiments, the operations as described above are implemented in two or more computer systems 1790.

Computer system 1700 is configured to receive information related to the instructions 1786 through I/O interface 1790. The information is transferred to processor 1782 via bus 1788 to determine corresponding adjustments to the transportation operation. The instructions are then stored in computer readable medium 1784 as instructions 1786.

Some embodiments include an integrated circuit. The integrated circuit includes a first set of conductive traces in a first level of the integrated circuit, the first set of conductive traces extending in a first direction, a second set of conductive traces in a second level of the integrated circuit different from the first level, the second set of conductive traces extending in a second direction different from the first direction. In some embodiments, the second set of conductive traces includes a first conductive trace of the second set of conductive traces corresponding to a gate terminal of a first p-type transistor and a gate terminal of a first n-type transistor, and a second conductive trace of the second set of conductive traces corresponding to a gate terminal of a second n-type transistor and a gate terminal of a second p-type transistor. In some embodiments, the first conductive trace of the second set of conductive traces and the second conductive trace of the second set of conductive traces are separated from each other in the first direction. In some embodiments, the first n-type transistor and the second p-type transistor are part of a first transmission gate. In some embodiments, the second n-type transistor and the first p-type transistor are part of a second transmission gate.

Some embodiments include a method of manufacturing an integrated circuit. The method includes positioning a first set of conductive features by a first mask, the first set of conductive features being in a first direction and a first level of the integrated circuit; manufacturing a second set of conductive features in a second direction different from the first direction, the second set of conductive features being in a second level of the integrated circuit, the second level being different from the first level. In some embodiments, the second set of conductive features includes a first conductive feature of the second set of conductive features corresponding to a gate terminal of a first p-type transistor and a gate terminal of a first n-type transistor, and a second conductive feature of the second set of conductive features corresponding to a gate terminal of a second n-type transistor and a gate terminal of a second p-type transistor. In some embodiments, the first conductive feature of the second set of conductive features and the second conductive feature of the second set of conductive features are separated from each other in the first direction. In some embodiments, the second n-type transistor and the first p-type transistor are part of a first transmission gate. In some embodiments, the first n-type transistor and the second p-type transistor are part of a second transmission gate.

Some embodiments include an integrated circuit. The integrated circuit includes a first active region, a second active region, a first transmission gate, a second transmission gate, a first gate structure and a second gate structure. In some embodiments, the first active region extends in a first direction, and being in a first level. In some embodiments, the second active region extends in the first direction, being in the first level, and being separated from the first active region in a second direction different from the first direction. In some embodiments, the first transmission gate includes a first PMOS transistor, and a first NMOS transistor. In some embodiments, the second transmission gate includes a second PMOS transistor, and a second NMOS transistor. In some embodiments, the first gate structure extends in a second direction different from the first direction, being in a second level of the integrated circuit different from the first level, overlaps the first active region and the second active region, and corresponds to a first gate of the first PMOS transistor and a second gate of the first NMOS transistor. In some embodiments, the second gate structure extends in the second direction, being in the second level of the integrated circuit, overlaps the first active region and the second active region, corresponds to a third gate of the second PMOS transistor, and being separated from the first gate structure in the first direction.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. 

What is claimed is:
 1. An integrated circuit, comprising: a first set of conductive traces in a first level of the integrated circuit, the first set of conductive traces extending in a first direction; a second set of conductive traces in a second level of the integrated circuit different from the first level, the second set of conductive traces extending in a second direction different from the first direction, the second set of conductive traces including: a first conductive trace of the second set of conductive traces corresponding to a gate terminal of a first p-type transistor and a gate terminal of a first n-type transistor; and a second conductive trace of the second set of conductive traces corresponding to a gate terminal of a second n-type transistor and a gate terminal of a second p-type transistor; wherein the first conductive trace of the second set of conductive traces and the second conductive trace of the second set of conductive traces are separated from each other in the first direction; the first n-type transistor and the second p-type transistor being part of a first transmission gate; and the second n-type transistor and the first p-type transistor being part of a second transmission gate.
 2. The integrated circuit of claim 1, further comprising: a first active region extending in the first direction, and being in a third level below the first level; and a second active region extending in the first direction, in the third level, and being separated from the first active region in the second direction.
 3. The integrated circuit of claim 2, further comprising: a third set of conductive traces in the first level of the integrated circuit, the third set of conductive traces extending in the first direction and being separated from the first set of conductive traces in the second direction.
 4. The integrated circuit of claim 3, further comprising: a first conductive feature extending in the second direction, being on a fourth level below at least the first level, and extending from at least the first active region to at least the second active region, wherein the first conductive feature corresponds to at least a source terminal of the first p-type transistor, a drain terminal of the second p-type transistor, a source terminal of the first n-type transistor or a drain terminal of the second n-type transistor.
 5. The integrated circuit of claim 3, further comprising: a first conductive feature extending in the second direction, being on a fourth level below at least the first level, and above the second active region, wherein the first conductive feature corresponds to a drain terminal of the first p-type transistor.
 6. The integrated circuit of claim 5, further comprising: a second conductive feature extending in the second direction, being on the fourth level, above the first active region, and being separated from the first conductive feature in at least the second direction, wherein the second conductive feature corresponds to a source terminal of the second n-type transistor.
 7. The integrated circuit of claim 6, further comprising: a first via electrically coupled between a first conductive trace of the first set of conductive traces and the first conductive feature; and a second via electrically coupled between the first conductive trace of the first set of conductive traces and a third conductive trace of the second set of conductive traces.
 8. The integrated circuit of claim 7, further comprising: a third via electrically coupled between the third conductive trace of the second set of conductive traces and a first conductive trace of the third set of conductive traces; and a fourth via electrically coupled between the first conductive trace of the third set of conductive traces and the second conductive feature.
 9. The integrated circuit of claim 3, further comprising: a first conductive feature extending in the second direction, being on a fourth level below at least the first level, and above the second active region, wherein the first conductive feature corresponds to a source terminal of the second p-type transistor.
 10. The integrated circuit of claim 9, further comprising: a second conductive feature extending in the second direction, being on the fourth level, above the first active region, and being separated from the first conductive feature in at least the second direction, wherein the second conductive feature corresponds to a drain terminal of the first n-type transistor.
 11. The integrated circuit of claim 10, further comprising: a third conductive feature extending in the second direction, being on the fourth level, and being separated from the first conductive feature and the second conductive feature in the first direction.
 12. The integrated circuit of claim 11, further comprising: a first via electrically coupled between a first conductive trace of the third set of conductive traces and the first conductive feature; a second via electrically coupled between the first conductive trace of the third set of conductive traces and the third conductive feature; a third via electrically coupled between the third conductive feature and a first conductive trace of the first set of conductive traces; and a fourth via electrically coupled between the first conductive trace of the first set of conductive traces and the second conductive feature.
 13. A method of manufacturing an integrated circuit comprising: positioning a first set of conductive features by a first mask, the first set of conductive features being in a first direction and a first level of the integrated circuit; manufacturing a second set of conductive features in a second direction different from the first direction, the second set of conductive features being in a second level of the integrated circuit, the second level being different from the first level, the second set of conductive features including: a first conductive feature of the second set of conductive features corresponding to a gate terminal of a first p-type transistor and a gate terminal of a first n-type transistor; and a second conductive feature of the second set of conductive features corresponding to a gate terminal of a second n-type transistor and a gate terminal of a second p-type transistor; wherein the first conductive feature of the second set of conductive features and the second conductive feature of the second set of conductive features are separated from each other in the first direction; the second n-type transistor and the first p-type transistor being part of a first transmission gate; and the first n-type transistor and the second p-type transistor being part of a second transmission gate.
 14. The method of claim 13, further comprising: positioning a third set of conductive features by a second mask, the third set of conductive features extending in the first direction, and being in the first level of the integrated circuit.
 15. The method of claim 14, further comprising: positioning a fourth set of conductive features in the second direction, and being on a fourth level below at least the first level, wherein a first conductive feature of the fourth set of conductive features corresponds to at least a source terminal of the first p-type transistor, a drain terminal of the second p-type transistor, a source terminal of the first n-type transistor or a drain terminal of the second n-type transistor.
 16. The method of claim 14, further comprising: positioning a fourth set of conductive features in the second direction, and being on a fourth level below at least the first level, wherein a first conductive feature of the fourth set of conductive features corresponds to a drain terminal of the first p-type transistor or a source terminal of the second p-type transistor; and wherein a second conductive feature of the fourth set of conductive features is separated from the first conductive feature of the fourth set of conductive features in at least the second direction, and the second conductive feature of the fourth set of conductive features corresponds to a source terminal of the second n-type transistor or a drain terminal of the first n-type transistor.
 17. The method of claim 16, further comprising: electrically coupling, by at least a first via, a first conductive feature of the first set of conductive features and the first conductive feature of the fourth set of conductive features; electrically coupling, by at least a second via, the first conductive feature of the first set of conductive features and a third conductive feature of the second set of conductive features; electrically coupling, by at least a third via, the third conductive feature of the second set of conductive features and a first conductive feature of the third set of conductive features; and electrically coupling, by at least a fourth via, the first conductive feature of the third set of conductive features and the second conductive feature of the fourth set of conductive features.
 18. The method of claim 17, further comprising: electrically coupling, by at least a first via, a first conductive feature of the third set of conductive features and the first conductive feature of the fourth set of conductive features; electrically coupling, by at least a second via, the first conductive feature of the third set of conductive features and a third conductive feature of the fourth set of conductive features; electrically coupling, by at least a third via, the third conductive feature of the fourth set of conductive features and a first conductive feature of the first set of conductive features; and electrically coupling, by at least a fourth via, the first conductive feature of the first set of conductive features and the second conductive feature of the fourth set of conductive features.
 19. An integrated circuit, comprising: a first active region extending in a first direction, and being in a first level; a second active region extending in the first direction, being in the first level, and being separated from the first active region in a second direction different from the first direction; a first transmission gate comprising: a first PMOS transistor; and a first NMOS transistor; a second transmission gate comprising: a second PMOS transistor; and a second NMOS transistor; a first gate structure extending in a second direction different from the first direction, being in a second level of the integrated circuit different from the first level, overlapping the first active region and the second active region, and corresponding to a first gate of the first PMOS transistor and a second gate of the first NMOS transistor; and a second gate structure extending in the second direction, being in the second level of the integrated circuit, overlapping the first active region and the second active region, corresponding to a third gate of the second PMOS transistor, and being separated from the first gate structure in the first direction.
 20. The integrated circuit of claim 19, further comprising: a third gate structure extending in the second direction, being in the second level of the integrated circuit, overlapping the first active region and the second active region, corresponding to a fourth gate of the second NMOS transistor, being separated from the first gate structure and the second gate structure in the first direction, the first gate structure being between the second gate structure and the third gate structure. 